Amyloid PET imaging images a radiotracer, such as 18F-AV-45 (a.k.a., Florbetapir F-18), which binds to extra-cellular amyloid brain plaques (i.e., amyloid β (AB) plaque), or hard insoluble protein fragments which lie between nerve cells. These extra-cellular amyloid brain plaques are considered a precursor of Alzheimer's disease. See Clifford R Jack, Jr. et al. Hypothetical model of dynamic biomarkers of the Alzheimer's pathological cascade. Lancet Neurol. 2010 January; 9(1): 119-28. Hence, amyloid PET imaging has a high negative predictive value for Alzheimer's disease if the images are correctly interpreted. Due to the expected increase in dementia incidents in the future, the role of Amyloid PET imaging is expected to increase.
Amyloid PET images can be interpreted by visual inspection. Visual inspection of the images is however hampered by different levels of amyloid tracer non-specific binding in white matter. This requires the reader to carefully inspect the images as to their grey matter uptake only. This is cumbersome and unreliable in the absence of brain tissue information.
With reference to FIGS. 1A and 1B, negative and positive amyloid PET scans, respectively, are shown. A negative amyloid PET imaging scan is a scan where β-amyloid plaque is not present, whereas a positive amyloid PET imaging scan is a scan where β-amyloid plaque is present. The scans were generated using 18F-AV-45. FIG. 1A acts as a control and illustrates that significant unspecific tracer uptake can only be found in white matter for a healthy brain. FIG. 1B illustrates that uptake can be found in white and gray matter for a brain suffering from amyloid plaque burden.
Image quantification can also be used to interpret amyloid PET images. However, image quantification suffers from the same problem of unspecific tracer uptake in white matter as visual inspection. Namely, amyloid images are typically quantified by determining the standardized uptake value ratio (SUVR) in different cortical areas with respect to a reference region, such as the cerebellum. Since unspecific white matter uptake is included in quantification, specificity and sensitivity decrease.
The present application provides a new and improved system and method which overcome the above-referenced problems and others.